Researchers measure carbon footprint of Canada hydroelectric dams

Researcher Michelle Garneau from the University of Quebec in Montreal tests soil in a peat bog to gauge the climate impact of the giant Romaine hydroelectric dam project

Squatting on spongy soil, a climate scientist lays a small cone-shaped device to "measure the breathing" of a peat bog in the northern part of Canada's Quebec province.

Michelle Garneau, a university researcher and a member of the UN's Intergovernmental Panel on Climate Change (IPCC), is collecting the first data on areas flooded to build the new Romaine hydroelectric dams in a bid to assess the project's impact on the region.

While renewable hydroelectricity itself is considered to be one of the cleanest sources of energy on the planet, there is currently no proven model for calculating the greenhouse gas emissions released by flooding huge areas behind new dams.

With construction of four new dams on the Romaine River in northern Quebec nearly complete, researchers saw an opportunity to try out new techniques to measure its carbon footprint.

The team led by Garneau zeroed in on a swamp a mere stone's throw from the raging river in the wilds of Canada's boreal forest, an area accessible only by helicopter.

After landing, she takes several boxes out of the belly of the aircraft and places them next to some solar panels and a portable weather station that she and her students installed over this summer.

The devices are expected to produce sample data within two years.

"Every 20 minutes, the cone will capture and measure the breathing of the soil," she explains, placing a transparent device that resembles a handbell on the lichen, as wild geese honk and cackle overhead.

Researcher Michelle Garneau's team is building a temporary weather station to record data from the area near the Romaine hydroelectric dam project in Canada's Quebec province

She takes a few steps further on the unstable ground and places a box that connects to sensors already sunk into the ground.

"This automated device to measure the photosynthetic activity records the CO2 and methane emissions every three minutes, for hours," the researcher says.

Another team is measuring carbon dioxide emissions from artificial lakes created by flooding lands behind dams, for eventual comparison.

More research needed

About one-third of the world's land area is covered by forests, which act as sinks for greenhouse gases.

Canada's vast boreal forest has trapped more than 300 billion tonnes of carbon dioxide, according to the Washington-based Natural Resources Defense Council.

However, 10 to 13 percent of Canada's boreal forest is covered by peatlands—wetlands with high levels of organic matter—and very little is known about them, says Garneau, research chair on peat ecosystems and climate change at the University of Quebec in Montreal (UQAM).

An aerial view with the Romaine River in the background and Hydro-Quebec's power line seen north of Havre-St-Pierre in Canada's Quebec province—climate scientists are trying to gauge the impact of a new hydroelectric dam project

Her work is supported by the province's utility Hydro-Quebec, whose dams—once the four additional hydropower plants on the Romaine River are turned on in 2019—will supply 90 percent of Quebec's power needs.

The data collected in this study should "serve the IPCC and the advancement of science in general" by helping to better peg the carbon footprint of flooded wilderness, Garneau told AFP.

The information is crucial with several new big hydroelectric projects due to come online in the coming years, including in Canada, the Democratic Republic of Congo, Ethiopia, Laos, Tajikistan and Zimbabwe.

"We're creating artificial reservoirs around the world, but GHG emissions from hydroelectricity are not well accounted for," said Paul Del Giorgio, a biologist at UQAM.

"There are some dams in tropical zones that emit as many greenhouse gases as coal plants," due to the accelerated decomposition of drowned organic materials, said the Argentine researcher.

Del Giorgio and his students complement Garneau's research by taking water samples from flooded lands behind dams that are analyzed in a field laboratory set up in Havre-Saint-Pierre's town hall.

Both datasets will be plugged into a complex set of equations to determine the volume of greenhouse gas emissions from dams.

The first results of their work are expected in 2019 and are highly anticipated by climate scientists worldwide, says Garneau.

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User comments

This article makes it sound like the CO2 continues coming out of the "decomposing material" in the water forever. No, after the initial drowned plant life is decomposed, that's it. Done. So, after the initial "burp" of CO2, that's it, clean hydro power from then on. Talk about making a mountain out of a molehill.

No, after the initial drowned plant life is decomposed, that's it. Done

Not quite. There is continuous sedimentation of new decomposing matter because the reservoirs are shallow at the upstream and large areas are continuously being drained and re-flooded as the reservoir level changes.

Wouldn't that be plant matte?. So the carbon would be captured when the level goes down, and the plants grow - and then released when flooded - and decomposed. Yes? Carbon neutral - yes?

In theory, although the carbon comes out as methane, so the dams basically convert CO2 to CH4 which is 30 times stronger as a greenhouse gas, and that effectively results in net GHG emissions - like adding a million cows to the environment.

Then there's the peatlands, which are acidic due to the peat basically pickling itself. That stops the decomposition of the peat and causes the peat to pile up, sequestering carbon. When you subject the peatlands to varying water levels, you're essentially rinsing the acid (and some of the peat) away and the rotting continues, releasing previously trapped carbon from the soil.

@Eikka - obviously a way more complex topic than we can adjudicate. Eg.

Methane is produced at the reservoir bottom. As it rises toward the surface most of the methane is oxidized in the water to carbon dioxide, a much less powerful greenhouse gas. But when methane-rich deep water is released at the dam the pressure acting upon it suddenly drops and most of its dissolved methane is released

So if the land is flooded - and there is an initial methane burp - some of that methane becomes C02 - some released as Methane. The gas production from the marginal areas we were talking about becomes even more complex. How much C02 is sequestered, vs how much is released as C02, and how much released as Ch4. Ch4 - while a more potent ghg, it stays in the atmosphere less time - so yet another compounding variable.

I am concerned about this study. It feels like a study sponsored by big oil to delay hydro production. A two year study delays everything by two years -- more CO2, yay! They measure one small aspect of the environment that may spit out a bit of CO2, but ignore all the other factors in the environment change that results from CO2. I doubt if any truly meaningful findings will result.

It reminds me of when "scientific studies" convinced George W. Bush to mess with daylight saving time. It was s'posed to save gazillions of energy and stuff. Did it? Nope. Ultimately it benefited one or two specific sectors, sectors that invested in the study in the first place.

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